scholarly journals Time budgets of Tibetan eared pheasants during the non-breeding season in an alpine scrub habitat

2009 ◽  
Vol 55 (3) ◽  
pp. 193-199
Author(s):  
Xin Lu ◽  
Guangmei Zheng

Abstract Time allocations of the group-living Tibetan eared pheasants Crossoptilon harmani with and without supplementary food were investigated by full-day sampling from winter through spring in an alpine scrub zone, south Tibet. At a flock scale, both the different food-supply flocks displayed similar daily patterns of activity, foraging in the morning and evening, and resting around midday. In terms of individual activity, either foraging or resting was highly synchronous with the flock’s. Non-provisioned birds spent more time feeding and less resting in midwinter than in late autumn. In early spring as climates became warmer and day longer, however, non-provisioned birds did not decrease their feeding efforts significantly but the provisioned birds did. Across the non-breeding seasons, the provisioned birds (relying on nutrition-rich artificial food) devoted less time to feeding and more to resting than did the non-provisioned ones (relying on nutrition-poor plant roots). Multivariate analysis showed increased food supply and ambient temperature resulted in a reduced foraging effort. However, the fact that the non-provisioned birds can save daily time for resting even in the cold short-day length mid-winter indicated that they faced no energetic constraint. Thus, protecting shelter vegetation rather than providing extra food is suggested to be important for long-term survival of the endangered galliform birds.

Nematology ◽  
1999 ◽  
Vol 1 (7) ◽  
pp. 717-726 ◽  
Author(s):  
Stefan-Andreas Johnigk ◽  
Ralf-Udo Ehlers

AbstractIntra-uterine birth causing maternal death (endotokia matricida) is relatively common in rhabditid nematodes and typical for entomopathogenic nematodes of the genus Heterorhabditis. A detailed description of this phenomenon is given, including a summary of embryo development, egg-laying, juvenile hatching and development. It is demonstrated that low food supply significantly promotes the beginning of endotokia matricida but has no influence on the time scale of the process. The biological function of endotokia matricida and the intra-uterine induction of the dauer formation is discussed. Endotokia matricida in Heterorhabditis spp. is a well synchronised process of the destruction of the maternal tissues correlated with the juvenile development including the uptake of the symbiotic bacteria by the late pre-dauer stage. It secures the development of dauer juveniles at a moment when the external food supply is reducing and provides offspring which are well equipped with energy reserves and symbiotic bacteria for long term survival and subsequent infection of insects in the soil. Endotokia matricida bei Hermaphroditen von Heterorhabditis spp. und der Einfluss der Nahrungsversorgung . - Der Schlupf juveniler Nematoden im mutterlichen Uterus mit anschliessender Totung des Muttertieres (endotokia matricida) ist relativ weit verbreitet bei rhabditiden Nematoden und typisch fur entomopathogene Nematoden der Gattung Heterorhabditis. Die Endotokia matricida wird beschrieben sowie die Embryonalentwicklung, das Eilegeverhalten, der Schlupf und die Entwicklung der Juvenilen. Der Beginn der endotokia matricida wird durch eine niedrige Nahrungsverfugbarkeit in der Kultur signifikant gefordert, diese hat jedoch keinen Einfluss auf den zeitlichen Ablauf der endotokia matricida. Die biologische Funktion der endotokia matricida und die intra-uterine Induktion der Dauerlarvenbildung werden diskutiert. Die endotokia matricida bei Heterorhabditis spp. ist ein gut synchronisierter Prozess, bei dem die Zerstorung des Muttertiers korreliert mit der Entwicklung der Juvenilstadien, einschliesslich der Aufnahme der symbiotischen Bakterien durch das Pra-Dauer Stadium. Sie sichert die Entwicklung von Dauerlarven zu einem Zeitpunkt, wenn die externe Nahrungsversorgung sich verschlechtert und bringt so Nachkommen hervor, die gut mit Energiereserven und symbiotischen Bakterien ausgestattet sind, um im Boden lange zu uberdauern und Insekten zu befallen.


2009 ◽  
Vol 296 (5) ◽  
pp. R1613-R1619 ◽  
Author(s):  
Matthew J. Paul ◽  
Jerome Galang ◽  
William J. Schwartz ◽  
Brian J. Prendergast

Many animals time their breeding to the seasons, using the changing day length to forecast those months when environmental conditions favor reproductive success; in Siberian hamsters ( Phodopus sungorus), long summer days stimulate, whereas short winter days inhibit, reproductive physiology and behavior. Nonphotic environmental cues are also thought to influence the timing of breeding, but typically their effects on reproduction are minor and more variable under categorically long and short photoperiods. We hypothesized that the influence of nonphotic cues might be more prominent during intermediate photoperiods (early spring and late summer), when day length is an unreliable predictor of year-to-year fluctuations in food availability. In hamsters housed in an intermediate photoperiod (13.5 h light/day), two nonphotic seasonal cues, mild food restriction and same-sex social housing, induced gonadal regression, amplified photoperiod history-dependent reproductive responses to decreasing day lengths, and prevented pubertal development indefinitely. These cues were entirely without effect in hamsters maintained under a long photoperiod (16 h light/day). Thus intermediate photoperiods reveal a heightened responsiveness of the reproductive axis to nonphotic cues. This photoperiod-dependent efficacy of nonphotic cues may explain how animals integrate long-term photic and short-term nonphotic cues in nature: intermediate day lengths open a seasonal window of increased reproductive responsiveness to nonphotic cues at a time when such cues may be of singular relevance, thereby allowing for precise synchronization of the onset and offset of the breeding season to local conditions.


2002 ◽  
Vol 38 ◽  
pp. 9-19 ◽  
Author(s):  
Guy S Salvesen

The ability of metazoan cells to undergo programmed cell death is vital to both the precise development and long-term survival of the mature adult. Cell deaths that result from engagement of this programme end in apoptosis, the ordered dismantling of the cell that results in its 'silent' demise, in which packaged cell fragments are removed by phagocytosis. This co-ordinated demise is mediated by members of a family of cysteine proteases known as caspases, whose activation follows characteristic apoptotic stimuli, and whose substrates include many proteins, the limited cleavage of which causes the characteristic morphology of apoptosis. In vertebrates, a subset of caspases has evolved to participate in the activation of pro-inflammatory cytokines, and thus members of the caspase family participate in one of two very distinct intracellular signalling pathways.


2000 ◽  
Vol 111 (1) ◽  
pp. 363-370 ◽  
Author(s):  
Katsuto Takenaka ◽  
Mine Harada ◽  
Tomoaki Fujisaki ◽  
Koji Nagafuji ◽  
Shinichi Mizuno ◽  
...  

2001 ◽  
Vol 120 (5) ◽  
pp. A747-A748
Author(s):  
S DRESNER ◽  
A IMMMANUEL ◽  
P LAMB ◽  
S GRIFFIN

2006 ◽  
Vol 175 (4S) ◽  
pp. 65-65
Author(s):  
Ashutosh K. Tewari ◽  
George Divine ◽  
Mani Menon

2006 ◽  
Vol 175 (4S) ◽  
pp. 355-355
Author(s):  
Manuel Eisenberg ◽  
John S. Lam ◽  
Rakhee H. Goel ◽  
Allan J. Pantuck ◽  
Robert A. Figlin ◽  
...  

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